Indeed, part of his appeal arguably was that he was someone who would not slavishly follow the party line, but rather speak his mind and not be afraid to cause the occasional headache for David Cameron and strategists at party HQ.
There are a couple of examples from the last fortnight of him doing just that: first, his continued support for a new airport in the Thames Estuary, and just last Friday, his announcement of a GLA inquiry into the benefits of an amnesty for illegal immigrants.
Part of his job as mayor is to act as a figurehead for the capital and to take a lead on a wide variety of issues – and Boris is clearly determined to do this, even in areas over which he has no direct jurisdiction.
But how far should he go? Is there a danger of him becoming too much of a maverick?